The general objective of the proposed research is to develop new types of organic molecules that can bind metal ions and transport them across membranes. One type of metal complexing agent, the torands, has a rigid cavity that is formed by the fusion of six- membered rings (pyridine and cyclohexane), resulting in a large, doughnut-shaped structure. Improvements in torand synthesis are proposed in order to prepare hexa-n-alkyl derivatives that may stack in columns, forming discotic mesophase liquid crystals. This molecular organization may constitute an important strategy for producing artificial ion channels. Also proposed are synthesis and complexation studies of larger ring "mixed heterocycle" torands that may display greater selectivity towards larger alkali metal ions, e.g. potassium relative to sodium. The new complexing agents will be tested as ionophores in liquid membrane ion-selective electrodes. The structures of complexes with various metal ions will be determined by X-ray crystallography and their stabilities will be measured by NMR and UV-VIS spectroscopy. Selective ionophores may be used to construct ion-selective electrodes for clinical analysis of metal ions in blood serum and urine.